2 Royal Enfields used to test new cylinder head design

The 2014 (left) and 2015 Continental GTs being tested in stock condition.
The 2014 GT got better mileage but the 2015 seemed to have more power.

Inventor and racer Shawn Chriswell plans to use two Royal Enfield Continental GTs to prove his patented cylinder head design gets better mileage and cuts emissions.

"We were awarded a National Science Foundation (NSF) award to verify that my technology works," Shawn wrote me in an email. "I need to prove that this is not some fluke that works on Harley-Davidson big twins only. So when looking for an air cooled fuel injected bike, I decided to use the Royal Enfield Unit Constructed Engine platform.

"More specifically we have two Royal Enfield Continental GTs. In the next few weeks I will finish the first prototype and have some initial test data.

"I have sort of fallen in love with these GT’s. I really love the marque."

That's why he wrote me, Shawn emphasized.

"I am not looking to launch this product here, and not looking for kudos in the RE community. I just think it could be a cool story about Royal Enfield."

Shawn runs DC's Machining, Inc. in Longmont, Colo., a business his father Darrell started in 1984 after retiring from Ball Aerospace Systems.

According to the website, their business is using precision machine tools to "work from CAD files to the occasional idea on a napkin to help bring your ideas into reality."

One such idea is their own new cylinder head.

An early prototype head for an 80-cubic-inch  Evo Harley-Davidson.
Ten thousand miles of testing left it looking clean.

Shawn and Darrell's Patent US 7258093 for a "Concave Combustion Chamber" is more unusual than its simple name implies. The cylinder head is divided in two by a ridge sticking down into the combustion chamber. One side of the ridge hosts a big intake valve. The other side sports two exhaust valves.

This means "The valves must criss-cross to open/close," the patent explains. "The result is a more efficient flow of intake air and exhaust air to and from the combustion chamber, which creates more horsepower."

Combustion ratio remains stock.

It already works on a Harley-Davidson, Shawn wrote me.

"I have a '96 2007 FXD that will get 64 mpg at 60 mph all the time."

"It would be really cool if we could impact the world in a good way with this technology," he said.

NEXT: Part 2 — How the project started

Part 3 — How it works